This invention relates to a trim adjust system for a watercraft and more particularly to an improved automatic trim adjustment and indicating system for a jet-propelled type of watercraft.
A popular type of propulsion system for watercraft, particularly small watercraft of the type known as personal watercraft, is a jet propulsion unit. These jet propulsion units are driven by a wide variety of prime movers and include a jet pump having an impeller that draws water through a water inlet opening and discharges it rearwardly through a discharge opening for providing a propulsion force for the watercraft. Frequently there is associated with the discharge nozzle a pivotally supported steering nozzle that pivots about a vertically extending axis for steering of the watercraft. In addition to this, it has also been proposed to provide a nozzle that is pivotal about a horizontally disposed axis so as to change the angle relative to the horizontal at which the water is discharged. By adjusting about this horizontal axis, the trim of the watercraft may be adjusted. Various mechanical and power-operated arrangements have been proposed for this trim adjustment, and these are very effective.
However, when the trim adjustment is employed, particularly when accomplished by a servomotor or the like, it is desirable if the operator is provided with some form of indicator that will indicate the trim adjusted position of the discharge nozzle. This permits the operator to determine what setting offers optimum performance and return to that setting if he desires. However, the previously proposed types of trim indicators have been generally mechanically operated and have not been particularly satisfactory for reasons which may be understood by reference to FIGS. 1 and 2, which show two different types of prior art mechanical type of indicators.
Referring first to FIG. 1, this figure merely shows the indicator, the servomotor, and its connection to a wire actuator, indicated generally by the reference numeral 11. The wire actuator is connected to the discharge trim adjusting nozzle in a manner which will become apparent in conjunction with the description of the preferred embodiment of the invention, as shown in FIG. 3.
A servomotor, indicated generally by the reference numeral 12, which in most prior art constructions comprises a reversible electric motor, has an output shaft 13 that is rotatable in opposite directions, as shown by the arrow 14. A screw 15, similar to a lead screw, is driven by the output shaft 13 and receives a nut member 16 which may be a recirculating type ball nut or the like. This nut member 16 has a lug 17 to which one end of the wire element 18 of the wire actuator 11 is connected in a well-known manner.
As the electric motor 12 is energized to rotate in either of the directions indicated by the reference numeral 14, the recirculating ball nut 16, which is held against rotation in a suitable manner, will move axially along the screw 15 and effect reciprocation of the wire element 18 so as to effect trim adjustment of the discharge nozzle.
A pinion gear 19 is affixed to the end of the motor shaft 13 at the end of the screw 15 opposite the drive motor 12. This pinion gear 19 is enmeshed with an internal gear 21 of a ring gear 22, which is supported for rotation within any suitable manner. The ring gear 22 is disposed so that its exterior surface on which a legend 23 is placed will be visible from the operator. Thus he can determine the angular position of the motor shaft 14 and, accordingly, the trim adjusted position.
FIG. 2 shows another prior art type of construction which is somewhat simpler in configuration and in which the extending lug 17 passes through an opening 31 in a member of the body of the watercraft, adjacent which an indicia 32 is provided. As the shaft 15 rotates, the nut 16 will move in the directions of the arrow 33, and the lug 17 will traverse the slot 31. By its position an operator can determine the trim adjusted condition of the discharge nozzle.
It should be readily apparent from these constructions that it is necessary to put the servo drive motor 12 and the wire actuator 11 and its connection to the lug 17 in a position adjacent the rider's compartment and adjacent the outer surface of the body of the watercraft. This is not always desirable, and it does not permit a great deal of latitude in the placement of the mechanism. Also, the relationship of the motor 12 relative to the push-pull cable 11 is also compromised by the prior art types of indicators.
It is, therefore, a principal object of this invention to provide an improved trim position indicator for the trim adjustment mechanism of a jet propulsion unit for a watercraft.
It is a further object of this invention to provide an improved trim position indicator for a jet propulsion unit that can be placed at any desired location without its operation being compromised.
In connection with the trim adjustment of a watercraft, and particularly small personal-type watercraft normally powered by a jet propulsion unit, the trimming adjustment can be very important in the proper running and handling of the watercraft. If the trim adjustment is too high (water outlet lifted too high), then the watercraft can be subject to porpoising. If, on the other hand, the trim is too low, then the watercraft may not be stable, particularly when operating in a forward direction at high speeds. Providing fixed trim adjustments also is not necessarily practical because of the small size of these watercraft. Different weight operators, or a different number of passengers can significantly affect the optimum trim. Also the optimum trim can vary with various watercraft conditions in addition to its loading, such as speed.
It is, therefore, a still further principal object of this invention to provide an improved automatic trim adjusting mechanism for a jet-propelled watercraft.
It is a further object of this invention to provide an improved and simplified automatic trim adjustment mechanism for a personal watercraft powered by a jet propulsion unit.
If the watercraft is provided with a preset trim adjustment, as discussed above, the trim condition may not be optimum for the particular running condition of the watercraft and its loading. Therefore, there is an advantage in permitting the operator to select the trim condition under certain running conditions and having the trim adjustment mechanism automatically set the trim when operating at these conditions. For example, it may be desirable to permit the operator to set the trim at planing and also the trim when operating at a low speed non-planing condition.
It is, therefore, a still further object of this invention to provide an improved automatic trim adjustment mechanism for a personal watercraft powered by a jet propulsion unit wherein the operator can select desired trim conditions at certain running conditions, with the trim being set automatically thereafter in response to the preset conditions.